The present claimed invention relates to the field of streaming media. More specifically, the present claimed invention relates to delivering streaming data to fixed clients and/or mobile clients using multiple description bitstreams and various forms of diversity.
Today""s networks, such as the Internet, are primarily designed for delivering static, non-real-time data to fixed clients such as desktop computers and laptops. Developing a system that delivers real-time streaming media to mobile clients presents an even greater series of challenges due to the streaming nature of the data and the mobility of the user. These challenges are intensified when considering issues such as system scalability, which extends service to a larger number of users; and quality-of-service and fault tolerance, which provides mobile users with continuous, uninterrupted streaming media sessions. Furthermore, this robust, uninterrupted media delivery session must be delivered over best-effort networks, which provide best effort, but non-guaranteed levels of service. A solution that overcomes these many challenges requires innovation throughout the end-to-end system.
Currently, multimedia applications such as video and audio communication over the Internet or wireless links are hampered by the limited bandwidth and losses (e.g. packet loss or bit errors) that afflict these error-prone environments. These multimedia applications require high compression and high error resilience, however simultaneously achieving these qualities is difficult because these are largely conflicting requirements.
Two important characteristics of a media communication system are reliability and efficiency. For the problem of streaming media from a wired infrastructure to a wireless mobile client, a sequence of operations is performed where each is a possible point of failure. The conventional approach to achieve reliability in such a system is by duplicating resources, e.g. xe2x80x9cmirrored serversxe2x80x9d or transmitting the same information twice. This approach can reduce the probability of certain failures by providing backups, however it is inefficient as it requires twice as many resources and is still susceptible to other single points of failure.
The following is a more specific example of a conventional approach to streaming media from a wired infrastructure to a wireless mobile client, and the problems associated therewith. Streaming media from a wired infrastructure to a mobile client involves operation of a sequence of modules. If all of these modules work properly, then the communication is successful. However, if any of these modules is faulty, then the entire communication is unsuccessful. For example, a typical communication may involve a server reading a media stream from storage, sending it over a wired network to a wireless base station, the wireless base station then transmits the stream over the wireless channel to the wireless client. This system involves the interaction of at least the following modules (1) storage, (2) server, (3) wired network, (4) wireless base station, (5) wireless transmission in wireless cells. If all of the modules work properly then the communication is successful, however if any module is faulty the communication is unsuccessful. In an effort to improve reliability system designers typically add redundancy to remove single point of failure. For example, two sets of any hardware may be used instead of one, e.g. two storage modules or two servers, which are xe2x80x9cmirroredxe2x80x9d to contain the same information. Similarly, the same information may be transmitted twice in the wired network. In addition, the wireless transmission, assuming CDMA and soft-handoff, typically involves two or more transmissions of the same information. In each of these conventional approaches, the improved reliability is achieved by duplicating the information and/or the resources.
While these conventional methods of duplication improve reliability, they are also inefficient because they use twice as many resources. In addition, this conventional approach may be ineffective if a single fault may afflict both duplicates. For example, if both storage modules (and/or both servers) are at the same location, a power outage or flood would render both of them useless. When the same information is transmitted twice in a wired network, the information typically proceeds along the same path in the network. Therefore, if that same path is congested or experiences an outage. then both duplicates of the information would be lost. To summarize, in an attempt to improve reliability the conventional approach is to duplicate information and resources. This conventional approach is inefficient because of the duplication, and is also ineffective because in many cases there can still exist single points of failure.
Although portions of the above-listed discussion specifically mention the shortcomings of prior art approaches with respect to the streaming of video data for simplified presentation, such shortcomings are not limited solely to the streaming of video data. Instead, the problems of the prior art span various types of media including, but not limited to, audio-based data, speech-based data, image-based data, graphic data, web page-based data, and the like. Moreover, streaming media typically shares the property that the media streams must be delivered with a relative time constraint and thus share the notion of a stream.
Thus, the need has arisen for a method and system for streaming media to fixed clients and/or mobile clients. A further need exists for a method and system for streaming media to fixed clients and/or mobile clients wherein the method and system provides increased reliability and efficiency over conventional systems.
The present invention provides a method and system for streaming media to fixed clients and/or mobile clients. The present invention further provides a method and system for streaming media to fixed clients and/or mobile clients wherein the method and system provides increased reliability and efficiency over conventional systems.
Specifically, in one method embodiment, the present invention recites encoding media data to be streamed to a client into a first multiple description bitstream and into a second multiple description bitstream. The present method then determines the appropriate plurality of servers from a network of servers onto which the first and second multiple description bitstreams should be distributed. The present embodiment then recites distributing the first and second multiple description bitstreams to the appropriate plurality of servers disposed at intermediate nodes throughout a network such that a client is provided with access to the media data via a plurality of transmission paths. The present method is also well suited to redistribution of multiple description bitstreams to servers based upon time-varying demand, client movement, and the like.
These and other technical advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.